Pain is one of the most frequent signs of a disease or a damage. Though pain is to be understood as a warning and protective function of the organism, patients concerned generally call for pain-killing or at least pain-relieving substances. For this reason, one of the most important concerns in medicine is to provide such substances. The function of these substances, so-called analgesics, is to reduce or suppress the sensation of pain when given in therapeutic doses without having a general narcotic effect in these doses. Based on their potency, therapeutic mechanism and side effects one distinguishes between two groups of analgesics: very potent analgesics acting on the central nervous system and low to moderately potent ones primarily having a peripheral action. Active substances acting on the central nervous system frequently involve a habit-forming potential which might develop into addiction. Morphine (Formula 3a) is one example of an active substance acting on the central nervous system and having such a risk. In the form of its inorganic salts, for example its hydrochloride or sulfate, morphine is commercially available for parenteral or peroral application to control acute posttraumatic or postoperative pain, as well as chronic pain, for example, in the state of advanced cancer.
A derivative of morphine, diacetylmorphine (Formula 3b), also known as diamorphine or heroin, is dealt and consumed among drug addicts without any pharmacological, pharmaceutical, or pharmacokinetic control. Its qualified use in the treatment of drug addiction is a scientific and sociological problem that has not yet been solved.
In order to reduce the risk of morphine dependence in the clinical use of morphine preparations, other analgesics, preferably non-narcotic peripheral preparations, are administered at the same time or alternately. Owing to the great variety of peripherally effective analgesics, their different potency and thus their different dosage, there is a great uncertainty concerning the choice of preparations to be combined, resulting in patient discomfort because of the amount of drugs to be taken.